667 



Some of the American Monkeys (Ateles), wliich are higher cephalised 

 tliaii the Monkeys of the Old Woi'hl, doI e.vcepted tJw Antliropoid 

 Apes, obtained a third prehensile and tonch hand in their tail. 



Man certainly likewise owes his iiigh rank to his hand ; his 

 cephalisation is almost equal to nearly four times that of Anthropoid 

 Apes, consequently he has risen still higher above the latter, than the 

 Squirrel above the Rat, or the Ele[)hant above the other Hoofed Mammals. 



Even in the Amphibia we see the cephalisation of the Treefrog, 

 which uses its fore-feet as hands, increasing considerably. 



Among Birds, Owls have a high cephalisation, not so much on 

 account of their large night-eyes, which cause only an enlargement 

 of the images on the retina (in comparison with the Day-Birds of 

 Prey), without augmentation of central nerve-cell mass, but on account 

 of the extremely developed sense of touch in the skin and their 

 very quick ear. The touch-corpuscles at the base of the feathers are 

 incredibly numerous. ^) 



The Parrots owe the high value of their /• to their handlike paw 

 and pincerlike beak. 



In all these cases greater influence of the factor S'^-^^- by speci- 

 fication of the organ of touch occurs. 



The comparatively high cephalisation of Sea-Mammals, usually 

 represented exaggerately (as few full-grown animals have been 

 examined), and that of the Hippotamus, however low in the general 

 organisation of the nervous system, can now easily be explained. 



According to the evidence now available, the coefficient of cepha- 

 lisation of Seals can be computed at 0.6, that of Toothed Whales 

 (Odontocetes) at 0.7 and that of Whalebone Whales (Mysticetes) at 

 0.4. Seals owe their high cephalisation certainly partly to the 

 specitically high dev'elopment of their sense of touch. But Odontocetes, 

 whose cephalisation is equal to that of Anthropoid Apes, lack 

 certainly a similar high development of the organ of touch. They 

 distinguish tliemselves from the plankton-eating Whalebone Whales 

 by seeking their subsistence at usually greater depth, even to where 

 perfect darkness prevails. In coimectio]i with this fact their eye is 

 smaller than that of Mysticetes, but they possess a still more developed 

 sense of hearing than the latter; in the quiet water of the great 

 deep this organ can function perfectly as a sense of room. In 

 all these Water-Mammals, but mostly in the Odontocetes amongst them, 

 the ear is the most important organ ^). It is doubtless the crepuscular 



1) E. KiisTER, Morphol. Jahrb. Bd. 34. (1905), p. 126. 



'-) G. BoENNiNGHAUs. Das Olir ties Zahnwales. Zoologisciie Jaiubüclier. BJ. 19 

 1904). p. 338—339, — Compare 0. Abel, Palaeobiologie. Stuttgart 1912, p. 458. 



